Heretofore others have proposed the use of a single belt drive for two-spindle mowers, two such constructions being shown in U.S. Pat. Nos. 3,461,654 and 4,068,452. A single belt drive for a three-spindle mower is shown in U.S. Pat. No. 2,872,831 wherein the laterally outwardly spaced spindles utilize a single sheave and the central spindle has a sheave with three grooves. In the construction shown in U.S. Pat. No. 2,872,831, it is necessary to place a severe twist in the single belt, which is viewed as having a detrimental effect upon the life of the belt and tends to cause the belt to roll over during operation. In U.S. Pat. No. 3,709,062, a single belt drive for a three-spindle mower is shown wherein a separating means is utilized to prevent the belt from rubbing against itself. The belt, instead, rubs against the separating device thereby generating heat and wear which are viewed as having a detrimental effect upon the useful life of the belt.